There is a need for a vessel which can be navigated on coastal shallow waters and when needed said vessel can rescue itself. For instance, the water depth of most estuarine and bay waters connected to deep waters range from two to five feet such as the Gulf of Mexico area. These estuarine and bay water bodies are well protected from waves and provide natural safe harbors. However, said water bodies cannot be used by most deep water vessels due to their deep draft. The present invention provides adjustable vessel draft making navigation possible in both shallow and deep waters without changing the total vessel weight or its given payload. The buoyancy and corresponding draft of the vessel is controlled by using adjustable vertical hulls or elastic secondary hull for safe operations and navigation in both shallow and deep waters for all purposes including seakeeping characteristics and dynamic stability. The present invention provides a vessel self rescue system which can also be used as a temporary means of navigation in shallow waters as needed. Prior art reviewed showed limited improvements to navigational capabilities of vessels of which examples are summarized below although they may be considered to be remote prior art.
U.S. Pat. No. 4,994,238 discloses a semi-submerged ship which has twin parallel sub-merged lower hulls spaced apart at least two hull widths with different fixed configurations.
U.S. Pat. No. 4,044,703 discloses a sailboat control apparatus which carries a pair of weighted complementary shaped keels for independent rotation about a common axis.
U.S. Pat. No. 2,850,747 discloses an amphibious catamaran which is also adapted for land travel with a fixed buoyancy configuration in water showing a combination of a catamaran and trailer in one.